Drafting system



23, 1955 B. BISINGER ET AL 2,715,754

DRAFTIING SYSTEM Filed Nov. 5, 1955 INVENTOR BE IPA/HARD B/Sl/VGER JACQUES F/G/ ATTORNEYS United States Patent DRAFTING SYSTEM Bernhard Bisinger, Stuttgart, Germany, and Jacques Figi, Gibswil, Switzerland, assignors to M. Earl Heard, J12, Lanett, Ala.

Application November 5, 1953, Serial No. 390,308

6 Claims. (Cl. 19130) This invention relates to drafting systems, and more particularly to a novel arrangement for the drafting of textile slivers, roving and the like. The invention is particularly adapted for the operations of doubling on drawing frames and extending on roving frames, and may be employed with equal utility in conjunction with comber draw boxes, spinning frames and other conventional units of the textile industry. This application is a continuationin-part of our copending application Serial No. 329,256, filed January 2, 1953, and now abandoned.

It is a primary object of the invention to provide a drafting system of novel and greatly simplified design, involving a minimum number of rolls and other parts. A related object is to provide a drafting system inexpensive to construct and maintain.

A further object of the invention is to provide a drafting system capable of high speed operation, while drafting with eficiency and uniformity hitherto not attainable. The eflicient, high speed operation is inherently maintained in the invention with a minimum of attention, with a minimum of laps or ends down.

Another object is to provide a drafting system in which the overall draft applied may be readily varied, merely by changing a single gear. Other objects will be in part obvious and in part pointed out hereinafter.

The invention and the novel features thereof may best be made clear from the following description and the accompanying drawing, in the figure of which a preferred form of the invention is diagrammatically illustrated.

Referring to the drawing, the drafting system comprises a three-roll unit designated generally as 10, including back and front bottom rolls 11 and 12 respectively, and a top roll 13 supported thereby. The back bottom roll 11 is of non-slip surface character, preferably a common fluted roll, and by way of specific example may be 1% inches in diameter. Front bottom roll 12 may be fluted, sand-blasted or of other non-slip surface character, or may be smooth, and in diameter is desirably equal to or slightly smaller than roll 11, for example 1 inch.

Top roll 13 of the three-roll unit is of considerably greater diameter than either bottom roll, for example 3 inches, although it may vary in diameter from about 1 /2 to about 3 times the diameter of the larger of them. The top roll 13 is of the soft variety, that is, composed of or covered with an outer layer 13' of yieldable, resilient material, such as cork, leather, natural or artificial rubber, or synthetic plastic material of the nature of polyvinyl chloride, polyvinyl alcohol and their derivatives. The top roll is supported entirely by the bottom rolls 11 and 12 of the unit, without any special guide means, whereby it may rotate freely without frictional or other restraint.

The top roll of the three-roll unit is relatively heavily weighted, whereby it maintains its position on and between the bottom rolls Without difficulty. The term weighted means that the top roll is inherently heavy, or alternatively has its weight supplemented by additional weights 14 depending from or attached to each end thereof. By way of specific example, the total Weight of the "ice top roll may be between and pounds, and may be achieved conveniently by using a 20 pound roll supplemented by an 18 pound or 20 pound weight attached to each end thereof.

By reason of its weight and surface character, the top roll 13 effects a nip 15 with bottom roll 11 and a nip 16 with bottom roll 12 which diflier essentially from point or line contact. That is, the heavily weighted top roll through its soft outer layer 13 engages the bottom rolls 11 and 12 in relatively wide areas or strips of contact, and the material engaged therebetween is nipped not at points, but over measurable distances.

The path and direction of material through the system is indicated by arrowed line 17. As shown, the sliver or roving being worked upon may be fed directly to and through the unit 10, and then passes to a delivery roll pair 18, 19. Lower roll 19 of the delivery roll pair may be a common fluted roll about 1% inches in diameter, and the upper roll 18 a conventional soft roll of equal diameter.

The spacing between the delivery roll pair and the three-roll unit 10 is conventionally adjustable, and selected to slightly exceed the staple length of the material being worked upon, by perhaps A inch. That is, the

delivery roll pair 18, 19 is disposed relative to front bottom roll 12 in such manner that the free material length between the three-roll unit and the delivery pair, the distance the material travels after emerging from nip 16 of the three-roll unit before entering nip 20 of the delivery pair, is equal to about the staple length plus A inch. This adjustment may be conveniently approximated by setting the centers of rolls 12 and 19 at the desired spacing.

The nips 15 and 16 of the three-roll unit are spaced apart a distance considerably exceeding the staple length. ln the illustrative example, bottom rolls 11 and 12 may be disposed with centers spaced apart a distance of 2% inches or more. As will be evident, this roll spacing effects not only a spacing between nips 15 and 16 considerably exceeding common staple lengths, but also provides a stable base for the top roll 13 which rides thereon. The bottom rolls 11 and 12 are desirably tangent to an overlying plane which is substantially horizontal, to further facilitate stable support of the top roll. In the drawing, this overlying plane is indicated by line 21. Nip 20 of the delivery roll pair may be disposed in or above plane 21, but desirably is disposed slightly, about A; inch, therebelow, whereby the material is caused to wrap around the front bottom roll 12 to a somewhat greater extent.

The bottom rolls of the three-roll unit are positively driven at different peripheral speeds by means of their trunnions 11' and 12, the peripheral speed of the front bottom roll exceeding that of the back bottom roll. The peripheral speed ratio between front and back rolls is greater than 1.0, but less than about 1.10, preferably within the range of from 1.05 to 1.08. The top roll 13 is frictionally driven by the bottom rolls 11 and 12, usually at an intermediate peripheral speed. The delivery roll pair is positively driven at a peripheral speed exceeding that of the front bottom roll 12, great enough to effect an overall draft in the system of normally 6 to 8 in the case of drawing frames and comber draw boxes, or up to 15 or more, as in the case of roving frames. The drives of front bottom roll 12 of unit 10 and lower roll 19 of the delivery pair may be linked through a draft change gear mechanism, which may be readily changed to vary the overall draft of the system.

As indicated, material to be drafted may be fed or delivered directly into nip 15 of the three-roll unit, and upon emergence from nip 20 of the delivery roll pair will be found to have been drafted with singular efiiciency and uniformity. Operating under a variety of conditions, the drafted product of the systemis found to exhibit a variation from perfect uniformity ranging h eb y; 3 22 t o t 1. the s v t h a e being m er ll b r h n th a h ev d i h se t ti onaldrafting equipment operating tinder identical conditions. The'economic and operational importance of the outstanding product uniformity achieved be evident to those skilled in the art. g I

drafted material emerging-from the delivery roll pair may be condensed by a trumpet, then passed through a calendar roll into a can, or handledinsimilar conventional fashion. Alternatively, the drafted material fromthe roll pair 18, 19 may pass throughonc or more additional roll pairs; one of which may apply additional, draft. As willb e apparent,tlie majonportion or the overall draft of the's ys'te'm 'is appliedbe tween nips1'6' and .D r afti'ng to a minor" extent is effected on the three r oll unit between its nipsls and 16. The primary function of the three-roll unitfho'wever, is fto efiectively' con'trol the material being handle d, particularly during high speed operation.

Du e 6111s 'surmenaiactr anon 111m) substantial fiber slippage may occur in the nip 15. In passage from "nip 15 to 'nip'16, theinaterial undermoderate drafting tension 'is' siipported against the underside of top r011 13. Even though the' frorit "bottom 011.12 of 'the unit be'smooth surfaced, substantially no slippage may occur in nip 16 due to the firm engagement of weighted roll13'. "Themajor drafting occurs i'n'the material emerging from" mp 16, whereat it is supported for a short distance by the upper surface of roll 12f The major function of the three-roll unit, accomplished primarily 'by its firm engagement of the material and the initial minor drafting effected therei'i1',is to' present the material forsnbsequent drafting in firmly controlled condition permitting highspeed,- uniform drafting.

While the theory of operation is not understood with certainty,it isbeIieVed that the differences in peripheral speeds between the top roll 1'3and the bottom rolls I1 land 12 ofthe three-roll unit are instrumental in effecting a gentle break draft on the material,"which is delive'red from the unit in the form of a 'well paralleled fiat ribbon. .Wh ile the fibers are too firmly engaged to be pulled through the nips and slip in the conventional sense, necessarily some slippage between fibers, or be= 't'ween fibers and rollsfmusfeccurin the nips 15 and V '16." This action appears'to; exert a controlled slip page" influence fon the material,contributing material- 1y to the novel functioning of the three-roll unit;

It will thus be seen that"there has been provided by thisinvention a structure in which the'fvariouS ob jects hereinbefore set forth',"tog'ether with" many practical advantages, are successfully achieved. 'As various 53.;

by, whereby the top roll forms spaced nips with said bottom rolls, the diameter of the top 'roll' considerably exceeding the diameter of each bottom roll, means for positively driving the bottom rolls at different speeds whereby the peripheral speed of the front bottom roll exceeds that of the back bottom roll by a ratio not exceeding about 1.10, and a delivery roll pair adjacent the front bottomroll of said'unit, the spacing between said delivery roll pair and said three-roll unit effecting a free material length therebetween slightly exceeding the staple length of the fiber being processed, and the spacing between nips of the three-roll-u'nit considerably exceeding said staple length.

2. Drafting system according to claim 1, wherein the overlying plane tangent to the bottom rolls of said three-roll unit is substantially horizontal.

3. Drafting system according to claim 1, wherein the overlying plane tangent to. the bottom rolls of said three-roll unit 'is' substantially horizontal," and the bottom roll of said delivery'roll pairis .disposedfslightl'yi belowsaid plane. H W I 4. Drafting system according to claim 1, wherein the backbott'omroll o'f;said' three-rollnnit and the bottom roll of said delivery 'roll pair are of non-slip character. f

5. A drafting system comprising a three-roll unit including laterally spaced and parallel bottom rolls and a resiliently surfaced weighted toproll 'supportedfther'eby, whereby the top roll forms spaced nips'with said bottom rolls, the diameter "of the top roll considerably exceeding the diameter of each bottom roll, means for positively driving the bottom rolls at different, speeds whereby the peripheral speed of the front bottom roll exceeds that of the back bottom rollby a ratio between about 1.05 and about 1.08, and adelivery roll pair adjacent the front bottom roll. ofv said unit, the spacing between said delivery roll pair and said three-roll unit effecting a free material length therebetween slightly exceeding the staple Iengthof the fiberbein'g'processed, and the spacingbetween nips of thethree-roll unit considerably exceeding said staple length.

6. A drafting 'systemcomprising a"th ree-rollunit including laterally sp'acedland parallel bottom rolls and a1 resiliently surfacedweighted top rolI supported thereby, whereby the top rollforms spaced nips with said bottom rolls, the diameter of theztop roll considerably exceeding the diameter of each bottom roll,means for positively driving the bottomv rolls at difierent'speeds wherebythe peripheral speed of the front bottom roll exceeds'that of the'back bottom roll and a delivery roll pair adjacent thefro'nt bottom 'rollof said unit, the spacing between said-delivery roll'pair andsaid three-roll unit effecting a freef material length therebetwe'en'at least substantially equal to the staplelength of'the fiber being processed, and the spacing between nips of the three-rollunit considerablyexceeding said staple length;

References Cited in-the fileof this patent UNITEDSTATESYBATENTS 

